I have managed to use a dremel and drill the balsa out and i have got nearly all the epoxy. I should be able to get a new piece to fit after a little sanding and i should also be able to re-attach it to the fin so maybe all is not lost. I have taken my time drilling all the wood out (all night) so i will have a fdew hours sleep and see what can be done but i think i have gotten away with it. i will let you know what happens in a few hours
thanks for your help
paul